The magazine Environment have published The Short List: The Most Effective Actions U.S. Households Can Take To Curb Climate Change. In it, the authors Gerald T. Gardner and Paul C. Stern discuss how people are willing to change their habits in order to use less energy, but either don’t know how or are acting ineffectively.

Most people emphasise visible changes, such as switching off a light bulb when leaving the room, but there are many “hidden” improvements to be made that can have a much greater effect on energy reduction. Gardner and Stern believe the media is partly to blame, with most information and articles offering advice in a “laundry list” format, with no indication as to the best actions to take. They propose to tackle this problem in a clear and logical manner: investigate different methods of cutting energy usage, and then rank them according to effectiveness.

They begin by looking at where our energy goes. In 2005 in the US, 38.6% of all energy use was by private motor vehicles – by comparison, the commonly attacked air travel was only 3.4%. The next largest use is in space heating, where 18.8% of energy goes to keeping houses warm. For the gadget lovers, TVs, computers and dishwashers barely break 3% when combined, so don’t feel too environmentally concious about that new HDTV.

Next up: what can be changed? It turns out there are a few surprises. Carpooling, commonly touted as a way to reduce vehicle emissions, turns out to be around a third less effective than buying a more fuel-efficient car. Upgrading from a car that gets 20 mpg to one achieving 30.7 mpg could save 13.5% of all the energy you use, whilst sharing your ride will only get you up to 4.2%. All in all, a more efficient car that is well maintained could save as much as one-fifth of your energy usage.

In the home, we see similar results. You could turn your thermostat down a bit at night in order to save 2.8%, but you’ll probably just forget or give up after a week or so. Install proper insulation in your attic however, and you can sleep easy knowing you’ll have saved up to 5% on your energy bill.

Encouraging efficiency rather than curtailment is the name of the game here. Improve the way your energy is used, and you won’t have to feel guilty about accidentally leaving the light on when you go on holiday. As an additional benefit, your electricity and gas bills will be permanently lowered – providing you remain in your house for long enough to recoup the initial costs of efficient replacements. It’s a similar idea to one I’ve discussed before [PDF].

So what are the top changes you can make? I’ve reproduced their list at the end of this post, but it isn’t as clear as it could be, so I’ll spell it out in the order you should follow:

Actions you can take now, with little or no cost

Carpool with a friend.

Replace 85% of all your old lightbulbs with energy savers

Get frequent tune-ups to maintain your car.

Turn down the thermostat two degrees during the day, and another two at night.